Thin mediums of material such as paper, film and fabric have many useful applications. Often images and information are recorded on such mediums. Where information regarding characteristics of a medium is known before an image is recorded on the medium, the recording process can be adjusted to improve the quality of the recording. Once a recording has been made on a medium it can be useful to associate information in a memory that is associated with the medium. Such information can include information that describes the chain of custody of the medium, the use of the medium, and who has accessed the medium. Other useful information can also be associated with the medium such as information that depicts information recorded on the medium. See for example, commonly assigned U.S. patent application Ser. No. 10/161,514, entitled Virtual Annotation of a Recording on an Archival Media, filed by Kerr et al. on Jun. 3, 2002.
It is known to use Radio Frequency Identification (RFID) tags to provide an electronic memory and communication capabilities that allow information to be associated with a medium electronically. Such RFID tags typically comprise three principal elements, an antenna and transponder that cooperate to send and receive electromagnetic fields containing information, and a memory that stores information received by the transponder and provides stored information for use by the transponder.
The RFID tag is adapted to exchange information with a co-designed reading/writing device. Information that is stored in an RFID tag that is joined to an item can later be used to track, identify and process the item. The RFID tag can also store other information that is to be associated with the item. A commercially available “TAG-IT INLAY”™ RFID tag available from Texas Instruments, Incorporated, Dallas, Tex., USA, can be used to provide identifying information about an item to which the RFID tag is attached. This relatively thin, flexible type of RFID tag can be used in applications that previously required a label or bar code. The RFID tags of the prior art are typically used for identification purposes, such as for employee badges, inventory control, and credit card account identification. The advantage of such RFID tags is that they are small in size, easy to communicate with and, unlike a bar coded item, do not require the item to be optically aligned to the reader or scanner.
RFID tags have been proposed for use in applications with passports and credit cards, such as is disclosed in U.S. Pat. No. 5,528,222 entitled Radio Frequency Circuit and Memory in Thin Flexible Package filed by Moskowitz et al. on Sep. 9, 1994. These devices are useful for tracking the location, characteristics and usage of documents, books and packages. For example, such tags can be used to track the location of documents and track the chain of custody of such documents within a document management system.
RFID tags are typically formed into a package such as an inlay, or a plastic, glass or ceramic housing. The RFID package is then joined to an item such as a document or book after the item has been fully assembled. The RFID tag often has an adhesive surface that is used to form a bond between the RFID tag and the item to which it is being joined. It is also known to use other ways of mechanically joining an RFID tag to an item. For example, an RFID tag can be joined to an item using a staple or other mechanical fastener.
There is room for improvement in this arrangement. For example, a poor bond or poor mechanical joint between the RFID tag and the item can result in separation of the RFID tag from the item. This can defeat the purpose of joining the RFID tag to the item. Further, joining an RFID tag to an item increases the cost of the combined RFID tag and item because the RFID tag must include the cost of both the base and the fastener and the cost of labor associated with joining the RFID tag to the item. These costs can become significant where RFID tags are to be joined to a multiplicity of individual items, such as for example, individual sheets of a medium such as film or paper.
Additionally, such RFID tags typically take the form of a patterned antenna located on a base having a transponder unit applied to the top of the antenna. Accordingly, such RFID tags have a non-uniform cross-sectional area. The non-uniform cross-section of the tag can make the tag vulnerable to incidental damage to contact during manufacturing, printing, use, storage and distribution. Further, such RFID tags can interfere with the appearance and use of the item.
One approach for solving these problems is to incorporate RFID tags inside an item such as an identification badge. In one example, a clamshell type of outer casing in which the RFID electronics and antenna are deposited is provided. An example of such an identification badge is the ProxCard II proximity access card sold by HID Corporation, Irvine, Calif., USA. Thinner cards are made by sandwiching the RFID electronics and antenna between sheets of laminate material. An example of such a badge is the ISO ThinCard also sold by HID Corporation. While this method of forming a card produces a card that is thinner than the clamshell type card, the card has an uneven cross-section with increased thickness in the area of the RFID electronics.
These techniques, however, are not feasibly applied to the task of forming a thin medium such as paper, film and fabric. Such thin mediums are typically fabricated in high volumes using coating, extrusion and rolling techniques to convert pulp, gelatin or other material into thin sheets of material that are then processed into useful forms. The addition of a clamshell type structure known in the art is not practical or economically feasible in this type of production. The alternative lamination approach of the prior art is also not preferred because the increased thickness and uneven cross section caused by the presence of RFID electronics and antenna sandwiched between laminations can interfere with subsequent fabrication processes causing damage to fabrication equipment, the RFID electronics, the antenna or to the medium itself. Further, this uneven cross section can interfere with imaging equipment when a laminated medium having the RFID electronics and antenna is passed through equipment such as a printer that uses a medium after formation. This interference can damage the RFID tag, the medium and the equipment that uses the medium. The uneven cross section also can create a less than desirable appearance for the medium and images that are subsequently recorded thereon. Also, the antenna required to allow communication with the RFID electronics can cause the medium to be considerably larger and higher in cost if the medium is required to be transparent such as would be required for mediums such as an x-ray, an overhead or a lenticular or other display.
Alternatively, RFID circuits or circuit components can be formed by printing conductive materials such as inks onto a surface of a medium. For example Parmond® VLTRFID circuit sold by Paralec Inc., Princetone, N.J., USA are made in the way other circuits can be made using conductor inks such as those sold by Flint Ink in Ann Arbor, Mich., USA. However, it can be difficult to use such printing techniques to form high density patterns of conductors on a medium particularly at high volume media production rates.
Thus, a need exists for a medium that has the ability to store and electronically exchange data. A need also exists for a medium with this ability that is also compatible with conventional web fabrication processes, or post fabrication uses of the medium. Further, a need exists for a medium that can provide an antenna or RFID electronics using essentially transparent structures if required.